The present invention relates to a filtering apparatus and method.
Solid-liquid separation and concentration technology play an important role in industry, especially in the treatment of fine particles and colloids from dilute suspensions. Chemical processes which filter volumes of liquid mixtures containing solid or cellular suspensions suffer severely from plugging and colloidal fouling of the filter medium. For example, an important factor contributing to the successful running of any reverse osmosis plant is the quality of the pre-treatment of the feed. Reverse osmosis depends on having a clean flow of water to the membrane surface. If this does not occur, the membrane will very quickly become fouled, leading to loss in water flux and the need for a complete replacement of the membrane. Other areas where this technology plays an important role are in biotechnological downstream processes, food and drink manufacture, the production of ultra-pure water for use in the semi-conductor industry, boiler feed water production and water flood injection for secondary recovery on off-shore oil production platforms. In a very large proportion of chemical processes there is a need to filter solids which have been used in the process or are created during the process away from the desired liquid which itself must be of the highest purity. Similarly, in the drinks industry, it is very often of the utmost importance to remove any solids, especially yeast, to give the highest quality drink. The present invention is directed to a method and apparatus for filtering, which term is used herein to include clarifying and polishing.
Existing processes have suffered a number of disadvantages particularly in removing the filtered solid material or filter cake, from the filtering medium and unless this can be satisfactorily carried out a high quality filtering cannot be successfully achieved.